Background and importance Porokeratosis is a rare group of diseases characterised by annular keratotic plaques due to altered skin keratinisation. It is associated with mutations in the mevalonate pathway that cause the accumulation of toxic metabolites in the skin and the lack of the end product, cholesterol. Due to the small number of cases, therapeutic options are limited. The dual combination of cholesterol with an HMG-CoA-inhibitor (to avoid accumulation of toxic metabolites) can be a promising strategy to improve cutaneous lesions.

Aim and objectives A 53-year-old male was diagnosed with perianal ptychotropic porokeratosis (PP) in 2012. He underwent multiple topical treatments: imiquimod, diclofenac, tacalcitol, calcipotriol, calcitriol and photodynamic therapy, all of which were unsuccessful. The pharmacy service was asked to develop a cholesterol 2%/lovastatin 2% ointment, based on a series of cases of other forms of porokeratosis, in which this formulation was successful.

Material and methods Design and validation of a topical formulation of cholesterol 2%/simvastatin 1%. Since lovastatin was not commercially available as a raw material in our setting, the equivalence was made to simvastatin (2:1).

Evaluation of the formulation’s effectiveness by physician global assessment (PGA) based on clinical appearance and patient adherence and tolerance by pharmacist interview.

Results Cholesterol 2%/simvastatin 1% ointment was formulated on a petroleum jelly basis, as this provides a source of lipids to the stratum corneum and helps improve skin barrier function. The galenic validation of the preparation – organoleptic characteristics (colour, odour, occlusiveness, extensibility and consistency), homogeneity of particles and exudation – was adequate and remained stable. A shelf-life of 6 months at room temperature, protected from light, was granted.

The patient self-applied the ointment twice a day for 6 months, and then once a day for the next 6 months. The lesions improved from a PGA of 3 to 1 and discomfort decreased. The patient tolerated well the treatment and showed adequate compliance (85%). He did not experience any adverse events and his satisfaction rating was 4.5/5.

Conclusion and relevance Cholesterol 2%/simvastatin 1% ointment improved both cutaneous lesions and symptomatology in a single patient with PP that had not improved with previous therapies, showing an adequate safety profile and low cost.

Conflict of interest No conflict of interest